E. histolytica, which is the causative agent of amoebiasis, inhabits the intestinal tract of nearly one-half billion people worldwide and leads to about 75,000 deaths per year (1). The majority of infected persons are asymptomatic carriers. Histolytica isolates from symptomatic individuals have been shown to differ in the electromobility of certain isoenzymes (zymodemes) from those of amoebae obtained from most asymptomatic carriers. This has been the basis for the designation of "pathogenic" and "non-pathogenic" strains (2). Clinical diagnosis of E. histolytica by zymodeme typing is slow, the process usually requiring several days to complete.
The connection between zymodemes and pathogenicity as well as its molecular basis is still unknown (3,4).